Keywords: Pyrido[2,3-b]pyrazine; Suzuki coupling; Buchwald-Hartwig coupling; anti-inflammatory; cytotoxic activities and In-silico studies

Abstract

A novel series of 3-substituted pyrido[2,3-b]pyrazine derivatives were synthesized using Suzuki and Buchwald-Hartwig coupling reactions. All the synthesized derivatives were screened for in-vitro anti-inflammatory activities as inhibitors of pro-cytokines TNF-alpha and IL-6. Among them, compounds 7a, 7b, 7d, 9a and 9c showed LPS-induced TNF-α secretion of 79 ± 1.2, 98.5 ± 1.6, 95.5 ± 2.1, 92.4 ± 1.9, and 88.9 ± 1.2 pg mL-1 respectively at a concentration of 20 μM. Similarly, compounds 7a, 7b and 7d, 9a and 9c showed LPS-induced IL-6 secretion of 59.5 ± 2.1, 77 ± 2.1, 89 ± 2.4, 65.4 ± 2.1, and 74 ± 1.9 pg mL-1 respectively at a concentration of 20 μM. In addition, the compounds were tested for cytotoxic activity against A549, MCF-7, K562 & Hela cancer cell lines and all the compounds showed good biological profiles on cancer cell lines. In silico studies revealed that compounds 9a and 9b could bind strongly with the active site of the TNF-α protein structure and formed three hydrogen bonds with Gln61, Tyr151 amino acids with binding energies of -5.9 and -5.7 kcal/mol. Compound 9b formed three strong hydrogen bonds with amino acids of the TGF-β protein with a binding energy of -6.0 kcal/mol. Compound 7e bound strongly with the KRAS protein structure, making seven strong hydrogen bonds with amino acids Gly13, Val29, Asn116, Asp119, Ser145 and Ala146, each with a binding energy of -8.0 kcal/mol. Compound 7b bound strongly with the KRAS protein structure, making four strong hydrogen bonds with amino acids Asn116, Lys117, Asp119, Ser145, each with a binding energy of -8.2 kcal/mol.